Method of applying an insulating element by adhesive bonding

ABSTRACT

A method of applying an insulating element by adhesive bonding in a waterproofing system, where at least the insulating element or the support on which it is applied is porous, the insulating element being bonded by means of an adhesive based on a bituminous emulsion having a maximum water content of 35% and containing a bitumen whose penetration is between 20 and 300 dmm.

RELATED APPLICATIONS

This application claims priority from and incorporates by reference PCT/BE2004/000021, filed Feb. 19, 2004, and EP 03075485.7, filed Feb. 19, 2003.

BACKGROUND AND FIELD OF THE INVENTION

The present invention concerns a method of applying, by adhesive bonding, an insulating element in a waterproofing system.

It is generally known how to use insulating elements in a waterproofing system. The latter system is as a general rule made impervious by the application, as a final layer, of a bituminous or synthetic waterproofing membrane. The insulating element is either bonded to an existing membrane or to a support and then covered with a new membrane. For the application of the known method, use is generally made of a solvent-based glue free from water or a dual or single-component setting glue. The presence of water is normally harmful in waterproofing systems.

The disadvantage of the known method using glue based on organic solvent is that the setting of the glue is very slow and requires a long drying period after application.

The aim of the invention is to produce a method of applying an insulating element by adhesive bonding where the setting time is shorter whilst using a glue where water replaces the volatile organic compounds.

SUMMARY OF THE INVENTION

To this end the method according to the invention is characterized in that at least the insulating element or the support to which it is applied is porous, the insulating element being bonded by means of a glue based on a bituminous emulsion having a maximum water content of 35% and containing a bitumen whose penetration is situated between 20 and 300 tenths of a millimetre (dmm). The use of a glue comprising a bituminous emulsion with a maximum water content of 35% guarantees rapid setting since one of the constituents of the waterproofing system is porous. Water, which is ecological, has rapid diffusion making it possible to achieve relatively short setting times. Since at least the insulating element or the support comprises a material porous to water, the latter can escape through this porous material. Given that the water can escape, it will not form an obstacle to the adhesion of the various layers to each other and therefore to the waterproofing system.

It should be noted that the patent U.S. Pat. No. 2,506,339 discloses a glue comprising a bituminous emulsion and having a water content. However, this patent does not disclose the use of this glue in a method of application by bonding an insulating element in a waterproofing system. In addition, there is no maximum level mentioned for the water since it is the water that determines the viscosity of the adhesive in the glue described in this patent. On reading this document, a person skilled in the art does not therefore obtain any teaching with regard to the use of an adhesive based on a bituminous emulsion for gluing the insulating elements in a waterproofing system, nor limiting the water content. On the contrary, a person skilled in the art is led to add water in order to manage the viscosity of the adhesive.

A first preferential embodiment of a method according to the invention is characterized in that the adhesive used comprises a gelling agent soluble in the aqueous phase. The gelling agent acts as a viscosity regulator. The fact that it is soluble in the aqueous phase allows good mixing with the water present in the bituminous emulsion used.

Preferably the emulsion used is of the anionic type. This ensures better stability of the emulsion over time.

A second preferential embodiment of the method according to the invention is characterized in that the adhesive used comprises, by wet weight, between 40% and 70% bitumen, between 10 and 30 kg/tonne of emulsifier, between 0% and 2% thickener and between 0% and 2% mineral filler. This makes it possible to produce a filler meeting the performance criteria.

A third preferential embodiment of a method according to the invention is characterized in that the adhesive comprises polymers, either in latex form in the aqueous phase or in the bituminous phase.

The adhesive can be applied in spots, in lines or in total adhesion. It is the waterproofing system that will define the best way of applying the glue.

The invention will now be described in more detail with the help of the description given below by way of example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The insulating element to be applied in the waterproofing system, such as a roof, is preferable formed by a panel or membrane. The insulating panel can be a porous panel comprising mineral wool and having porosity to air and water. The porosity, defined by the value μ, is preferably between 1.1 and 1.3. According to another embodiment, the insulating panel comprises expanded perlite (μ approximately 5). The panel can also be non-absorbent or non-porous, for example comprising polyurethane, polyisocyanide, or expanded polystyrene surfaced with a sheet of glass, bituminous or not. The panel can also be covered with a sheet of aluminium.

When the waterproofing element is formed by a waterproofing membrane, this membrane is preferably a bituminous membrane that, where applicable, forms the existing roof. If the membrane forms the insulating element to be bonded, the support on which the bonding is carried out must necessarily be porous to allow the discharge of water as will be described below.

The insulating panel can be bonded on various supports such as for example concrete, bricks, wood, a steel box or other metallic structure, or a roof covered with a bituminous membrane. If the support is absorbent as in the example of concrete, the panel may be of the porous or non-porous type. On the other hand, if the support is non-absorbent, as in the example of the box or membrane, the panel must be porous at least at the area of contact with the adhesive.

The adhesive used for applying the insulating element is an adhesive based on a bituminous emulsion having a maximum water content of 35%. In other words the dry weight of the emulsion is situated between 40% and 85% with a preference for 60% to 70%. The adhesive must also have a degree of penetration of between 20 and 300 dmm (tenths of a millimetre), preferably between 70 and 100 dmm, in order to be able to adhere to the insulating element suitably.

The adhesive preferably comprises a gelling agent soluble in the aqueous phase in order to mix well with the bituminous emulsion forming the base of the adhesive. As a gelling agent, clays, preferably natural clays of the bentonite or sepiolite type or having chemically modified organic functions, can be used. These clays are not only a gelling agent but a mineral filler. The clays can also increase the stability under storage and act as a viscosity regulator for the adhesive. The quantity of gelling agent used comprises between 0% and 10% and preferably between 2% and 5% of the weight. Other mineral fillers can form part of the adhesive to be used. These are for example formed by slate powder. The quantity used is for example between 0% and 25% of the weight. It is also possible to use cellulose fibres or fibres of polyethylene as a filler. These form for example 0% to 5% of the weight. In general the total filler in the adhesive is between 0% and 20% of the weight of the adhesive.

The adhesive also comprises between 10 and 30 kg/tonne of the emulsifier, for example formed from quaternary ammonium salts, between 0% and 2% of thickener, for example formed from hydroxyethyl or propyl cellulose or bentonite, 40% to 70% of the weight of the adhesive is formed by bitumen.

The bituminous emulsion is preferable of the anionic or non-ionic type, which provides better stability of the emulsion over time. This is because emulsions of the anionic or non-ionic type afford good interaction with the filler or the gelling agent and promote stability of the adhesive. However, emulsions of the cationic type can also be used but their stabilisation is more difficult.

The adhesive can also comprise polymers of the elastomeric type, such as for example SBR.

The viscosity of the adhesive can be regulated by varying its proportion of water and its proportion of gelling agent. Thus, for example, for an application in full, the viscosity must be situated between 5 and 50 Pa.s, which allows application by scraper or by spraying. For application in lines, the viscosity will be situated between 50 and 400 Pa.s, and greater than 400 Pa.s if application is made in spots. The addition of 1.5% of cellulose fibres makes it possible to change from 5 Pa.s to a value of 60 Pa.s. The viscosity is measured at 20° C. at a shear speed of 5 sec-1.

When panels must be bonded on a support that is not uniformly flat, such as for example a steel box, the adhesive will preferable be applied to the support in lines having a weight of 100 to 300 g/ml and preferable 150 to 200 g/ml (grams/linear metre) with an applied quantity of 1 to 2.5 kg/m2, preferably 1.5 kg/m2. In this example, per profile of the structure, a minimum of one double line of adhesive is applied. When the adhesive is applied in spots, 1.5 kg/m2 is applied. The adhesive can also be applied by spraying, in particular when the entire surface of the support is to be coated.

For the application of bituminous membranes the adhesive is applied in lines or solidly and by quantities of 1.5 kg/m2.

The adhesive sets rapidly, in particular within 24 hours, and at a maximum after 72 hours after application for a temperature of 20° C., 70% to 80% of the maximum strength of adhesion is achieved. The maximum strength is obtained after approximately 1 week at a temperature of 20° C.

Since the adhesive contains water as a solvent it is very ecological. Despite the fact that the insulating element is used in a waterproofing system, the water present in the adhesive does not constitute a problem. Since one of the elements, either the insulating element or the support, or even both, are absorbent with respect to water, the latter can diffuse in the system through the element that absorbs water or which is porous to water. The setting speed will be all the more rapid, the greater the diffusion capacity of the assembled elements.

Even if the use of a bituminous emulsion in a waterproofing system is in principle a heresy, the results of tests carried out have proved the contrary. This is because, in a waterproofing system where at least one of the two parts to be put in contact is porous, an important performance of the adhesion in a reduced time compared with organic solvents has been found. Wind Tunnel tests (WIND UPLIFT TESTS, ETAG 006 March 2000) gave the following results:

EXAMPLE

Model for detachment in wind—Comparison of emulsion glue—solvent glue (a)

Steel box—mechanically fixed mineral wool insulator—emulsion glue—waterproofing membrane.

After 1 month of application: 6500 Pa (3500 Pa)(a)

After 4 months of application: 6000 Pa (6500 Pa)(a)

(a): Same Waterproofing System but with Glue with Organic Solvent

Even if the performance is good, the objective is to have the least water possible in the system. This is because the adhesion will be all the more rapid, the lower the percentage of water. This adhesion has been validated with a percentage of water in the adhesive at a maximum of 35%.

The adhesive can be applied in lines, in spots or in total adhesion according to the roof system. The difference in the application method is related to the rheology of the adhesive, which is modified not by the addition of water but by the type of additive.

Example 1

Thixotopic effect but by addition of organically modified smectite or bentonite. This type of additive will be used mainly for glues that can be used in lines or spots.

Example 2

Newtonian effect by the addition of attapulgite. This type of additive will be used mainly for glues that can be used in total adhesion on a support.

For greater versatility in the period of use, in particular in winter, it is possible to add antifreeze to the aqueous phase.

To increase the speed of evaporation of the water trapped in the system, it is possible to add a solvent creating a minimum azeatrope to the aqueous phase, that is to say the boiling point of the mixture of water and solvent is lower that 100° C. 

1-10. (canceled)
 11. A method of applying an insulating element in a waterproofing system, by adhesive bonding, comprising applying an adhesive composition to a support element and applying the insulating element thereto, wherein at least one of the support element and the insulating element is porous, and wherein the adhesive composition is a bituminous emulsion adhesive composition comprising: (a) up to 35% by weight water; (b) a bitumen having a penetration value of about 20 to about 300 dnm; and (c) an emulsifier.
 12. The method according to claim 11 wherein the bituminous emulsion adhesive composition further includes up to about 10% by weight of a thickening agent in the water phase.
 13. The method according to claim 11 wherein the bituminous emulsion adhesive composition further includes up to about 25% by weight of a filler.
 14. The method according to claim 11 wherein the emulsifier is an anionic emulsifier.
 15. The method according to claim 11 wherein the emulsifier is a non-ionic emulsifier.
 16. The method according to claim 11 wherein the adhesive composition comprises up to about 35% by weight water, about 40% to about 70% by weight bitumen, about 10 to about 30 kg/tonne emulsifier, about 2% to about 5% by weight of a thickening agent, and up to about 20% by weight of a filler.
 17. The method according to claim 16 wherein the adhesive composition further includes an elastomeric polymer.
 18. The method according to claim 16 wherein the adhesive composition has a viscosity of about 5 to about 400 Pa.s.
 19. The method according to claim 11 wherein the adhesive composition is applied to the support element in spots.
 20. The method according to claim 11 wherein the adhesive composition is applied to the support element in lines.
 21. The method according to claim 16 wherein the adhesive composition is dried for about 72 hours at about 20° C. to achieve at least 70% of maximum tear resistance for the waterproofing system. 